This invention relates to connectors and adapters for optical fibers. More particularly, this invention relates to adapters which provide attenuation in addition to optically connecting the terminal ends of optical fiber held by a pair of optical fiber connectors.
A wide variety of optical fiber connectors and corresponding adapters are known for the connecting of optical fiber. Many of these are industry standards and others are proprietary in nature. Regardless of the design, these connector/adapter combinations accomplish the same basic function: aligning two terminal ends of optical fiber to come into optical contact with one another and allow light passing through one fiber to be transmitted to the other fiber.
In many instances, an attenuation effect is needed in the optical pathway. It is known to have an attenuator held within the adapter to provide attenuation in the optical pathway between the two optical fiber connectors. Fiber optic attenuators induce a calibrated fixed loss between two connectors, which dampens (attenuates) the fiber optic signal. Attenuation is needed when an optical signal has too much power and exceeds the operating range of the equipment being connected. Without attenuation, the result can be saturation of the signal and induction of system errors or failures.
Attenuation within optical fiber networks can be achieved in several ways. Since bends in the optical fiber cable can cause some attenuation, it is known to provide a block for creating artificial bends in an optical fiber cable. Alternatively, an attenuator can be spliced into the optical fiber cable itself. Another option is to have attenuation built into an in-line device.
Fiber optic connection systems often will include a split sleeve within the adapter. The split sleeve is sized and positioned to receive the ferrules containing the terminal ends of optical fibers of each of a pair of fiber optic connectors. The split sleeve functions to hold these ferrules and the terminal fiber ends so that the ends are aligned and permit the optical connection of the cables attached to these connectors. The terminal end of each of the optical fibers are typically held in physical contact with one another to ensure the optical connection does not adversely affect the magnitude and accuracy of the signal being carried by the optical fiber.
It is known to interpose an attenuation medium between the terminal ends of the optical fiber to achieve a desired level of signal attenuation. U.S. Pat. Nos. 4,717,234 and 5,082,345 disclose connector and adapter combinations that provide an attenuator situated between the respective terminal ends of optical fiber and in physical contact with the terminal ends. Further, attenuators are desired for attenuating the signal between the terminal ends of the fibers to address such concerns as ease of assembly, ease of use, and availability for use with terminal ends which are angled.
One aspect of the invention relates to a fiber optic device for optically connecting fiber optic cables including an adapter for receiving fiber optic connectors which are attached to fiber optic telecommunications cables. The fiber optic connectors include ferrules which hold the terminal ends of the optical fiber of the optical cable. The fiber optic adapter includes a housing which forms a longitudinal opening through the adapter. Held within the longitudinal opening of the adapter is a fiber coupling mechanism including a hollow sleeve for receiving the ferrules and the terminal ends of the optical fiber of the connectors and aligning the optical fibers. In this sleeve are slots on opposite sides for placing an attenuator across the sleeve between the terminal ends of the optical fiber. This attenuator extends beyond the outer wall of the sleeve to engage pockets in the inner wall of the longitudinal opening, thus preventing the attenuator and sleeve from rotating within the longitudinal opening.
The slots in the sleeve may be directly across from each other to hold the attenuator perpendicular to the longitudinal axis of the sleeve. Alternatively the slots may be offset longitudinally to hold the attenuator at a non-perpendicular angle to the longitudinal axis of the sleeve, such as about 8 degrees from perpendicular for use with an angled physical contact (APC) connector.
A further aspect of the invention is to provide the fiber optic adapter described above without the optical fiber connectors. This adapter includes a housing forming a longitudinal opening through the adapter, a sleeve positioned within the longitudinal opening, and an attenuator inserted through the sleeve, extending beyond the outer wall of the sleeve and engaging pockets formed in the inner wall of the longitudinal opening, thus preventing the sleeve from rotating within the longitudinal opening. The slots in the sleeve of this adapter may be placed directly opposite each other across the sleeve to hold the attenuator at an angle perpendicular to the longitudinal axis of the sleeve. Alternatively, the slots in the sleeve may be longitudinally offset from each other so as to hold the attenuator at a non-perpendicular angle to the longitudinal axis of the sleeve, such as at an angle of 8 degrees for use with APC connectors.
A further aspect of this invention is method of assembling a fiber optic housing forming a longitudinal opening through the adapter with a sleeve placed within the longitudinal opening and an attenuator inserted through slots in the sleeve and extending across the longitudinal opening.
A variety of advantages of the invention will be set forth in part in the description that follows, and in part will be apparent from the description, or may be learned by practicing the invention. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.